76-carat diamond nets a record $21.5M

In this Oct. 4, 2012, photo, a model holds the Archduke Joseph Diamond, a historical diamond, during a Christie's auction preview, in Geneva, Switzerland. On Nov. 13, 2012, Christie's has auctioned off the famed Archduke Joseph Diamond for $21,474,525 including commission, a world auction record price per carat for a colorless diamond.The price was well above the expected $15 million and more than triple the price paid for it at auction almost two decades ago. The 76.02 carat diamond, with perfect color and internally flawless clarity, came from the ancient Golconda mines in India. In 1993, Christie's auctioned it in Geneva where it sold for $6.5 million.

Credit: AP Photo/Keystone/Laurent Gillieron

In this Oct. 4, 2012, photo, a model holds the Archduke Joseph Diamond, a historical diamond, during a Christie's auction preview, in Geneva, Switzerland.

Credit: AP Photo/Keystone/Laurent Gillieron

In this Oct. 4, 2012, photo, a model holds the Archduke Joseph Diamond, a historical diamond, during a Christie's auction preview, in Geneva, Switzerland.

Credit: AP Photo/Keystone/Laurent Gillieron

In this Oct. 4, 2012, photo, a model holds the Archduke Joseph Diamond, a historical diamond, during a Christie's auction preview, in Geneva, Switzerland.

Credit: AP Photo/Keystone/Laurent Gillieron

This Nov. 9, 2011, photo, shows a model displaying a 110.03 carats Sun-Drop Diamond of South Africa described as fancy vivid yellow, the highest color grading by gemstone experts at a Sotheby's preview show in Geneva, Switzerland. In November 2011, the Sun-Drop Diamond was sold for more than $10.9 million at auction, beating previous records for a jewel of its type.

Credit: AP Photo/Anja Niedringhaus

This Nov. 9, 2011, photo, shows a model displaying a 110.03 carats Sun-Drop Diamond described as fancy vivid yellow, the highest color grading by gemstone experts at a Sotheby's preview show in Geneva, Switzerland.

Credit: AP Photo/Anja Niedringhaus

This Oct. 25, 2010, photo, shows an employee of Sotheby's auction house holding a 24.78 carat fancy intense pink diamond mounted as a ring, that was last seen on the market some 60-years-ago according to the house, ahead of an auction in central London. In November 2010, a rare pink diamond smashed the world record for a jewel at auction, selling for more than $46 million to a well-known gem dealer. London jeweler Laurence Graff paid $46,158,674 for the diamond, which he immediately named "The Graff Pink."

Credit: AP Photo/Lefteris Pitarakis

In this May 2, 2012, photo, an employee shows the Beau Sancy diamond, 34.98 carat, at Sotheby's auction house in Zurich, Switzerland. In May, Sotheby's sold the Beau Sancy diamond to an anonymous bidder for $9.7 million. Marie de Medici had wore it at her coronation as Queen Consort of Henry IV in France in 1610. Then the diamond passed among the royal families in France, England, Prussia and the Netherlands. It was sold by the Royal House of Prussia.